The semiconductor and microchip industries rely on a number of chemical-mechanical planarization (CMP) processes during device manufacturing. These CMP processes are used to planarize the surface of a wafer in the fabrication of integrated circuits. Typically, they utilize an abrasive slurry and polishing pad. During the CMP process, materials are removed from the wafer and the polishing pad, and byproducts are formed. These can all accumulate on the polishing pad surface, glazing its surface and degrading its performance, decreasing its lifetime, and increasing wafer defectivity. To address these issues, pad conditioners are designed to regenerate the polishing pad performance through an abrading mechanism which removes the undesirable waste accumulations and recreates asperities on the polishing pad surface.
Most commercially available pad conditioners have industrial diamond abrasive bonded into a matrix. Typical matrix materials include nickel chromium, brazed metal, electroplating materials, and CVD diamond film. Due to the irregular size and shape distributions of diamonds as well as their random orientations, various proprietary processes have been devised to precisely sort, orient or pattern diamonds and to control their height. However, given the natural variation in diamond grit, it is not unusual that only 2-4% of the diamonds actually abrade the CMP pad (“working diamonds”). Controlling the distribution of cutting tips and edges of the abrasives is a manufacturing challenge, and contributes to variation in pad conditioner performance.
In addition, current matrix and bonding methods can also limit the size of diamonds that can be embedded. For example, small diamonds of less than around 45 microns can be difficult to bond without burying them within the matrix.
Acidic slurries for metal CMP can also pose challenges to traditional pad conditioners. The acidic slurries can chemically react with the metal bonding matrix, weakening the bond between the matrix and abrasive particles. This can result in detachment of the diamond particles from the conditioner surface, resulting in high wafer defect rates and potentially scratches on the wafer. Erosion of the metal matrix can also result in metal ion contamination of the wafer.